Global Signal Regression for ALFF/fALFF data

Submitted by MariaS on

Hi All,

We are currently debating whether to use global mean regression for the preprocessing to calculate ALFF/fALFF values. During this discussion we were wondering if there are any group differences in the global signal between our two groups. I thought the easiest way is to take the information about the global signal out of the Covariates.txt the DPARSF toolbox is creating for the nuisance regression, however as I’ve got 11 columns in the file for each subject, I am not quite sure which column corresponds to which covariate (in the toolbox we chose CSF WM and GSR and I guess there should also be some motion parameters in there?).

In any case I am not quite sure what to do with this information. Is this of interest? Does it mean I can’t use the GSR or should use it?

Hope anybody can help

Cheers

Maria

YAN Chao-Gan

Fri, 04/15/2016 - 02:22

Hi,

Global signal is the last  column. Actually, you can simply check off GSR checkbox.

GSR can reduce motion effect for ALFF/fALFF, see Yan, C.G., Cheung, B., Kelly, C., Colcombe, S., Craddock, R.C., Di Martino, A., Li, Q., Zuo, X.N., Castellanos, F.X., Milham, M.P., 2013. A comprehensive assessment of regional variation in the impact of head micromovements on functional connectomics. Neuroimage 76, 183-201.

Best,

Chao-Gan